Rotary piston engine of trochoidal construction with a follower gearing traveling in guide rods and forcibly effecting the piston movements

ABSTRACT

This invention relates to an improvement in a rotary piston engine of trochoidal construction having a follower drive forcibly effecting the piston movements and traveling on guide rods, the improvement comprising a cylindrical body means nonrotatably mounted on the engine drive shaft and eccentrically offset with respect thereto by the extent of the trochoid eccentricity, and sleeve means rotatably mounted on said cylindrical body means and serving as a carrier for elements of the follower drive non-rotatably connected thereto, and for the piston.

United States Patent 11 1 Hiif [ Sept. 30, 1975 1 1 ROTARY PISTON ENGINE OF TROCHOIDAL CONSTRUCTION WITH A FOLLOWER GEARING TRAVELING IN GUIDE RODS AND FORCIBLY EFFECTING THE PISTON MOVEMENTS [75] Inventor:

[73] Assignee: Dornier System GmbH., Germany [22] Filed: Oct. 12, 1973 21 Appl. No.: 405,875

Franz Hiif, Constance, Germany [30] Foreign Application Priority Data Dec. 16, 1972 Germany 2261670 [52] US. Cl. 418/61 B; 418/94 [51] Int. Cl. F04C 1/00 [58] Field of Search 418/58, 61 R, 61 B [56] References Cited UNITED STATES PATENTS 298,952 5/1884 Donkin 418/58 11/1932 Eyston 418/58 X 3/1974 Huf 418/129 Primary E.\'aminerC. J. Husar Assismn! EvaminerLeonard Smith Attorney, Agent, or Firm.lames E. Bryan 5 7 1 ABSTRACT This invention relates to an improvement in a rotary piston engine of trochoidal construction having a follower drive forcibly effecting the piston movements and traveling on guide rods, the improvement comprising a cylindrical body means non-rotatably mounted on the engine drive shaft and eccentrieally offset with respect thereto by the extent of the trochoid eccentricity, and sleeve means rotatably mounted on said cylindrical body means and serving as a carrier for elements of the follower drive nonrotatably connected thereto, and for the piston.

3 Claims, 4 Drawing Figures US. Patent Sept. 30,1975 Sheet1of4 3,909,163

U.S. Patent Sept. 30,1975 Sheet 2 Of4 3,909 163 I I I I I I I I I I I I I l I I I I I I U.S. Patent Sept. 30,1975 Sheet 3 0f 4 3,909,163

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Patent Sept. 30,1975

Sheet 4 of 4 ROTARY PISTON ENGINE OF TROCI-IOIDAL CONSTRUCTION WITH A FOLLOWER GEARING TRAVELING IN GUIDE RODS AND FORCIBLY EFFECTING THE PISTON MOVEMENTS The present invention relates to a rotary piston engine of trochoidal construction. In these engines, the number of revolutions and the direction of rotation of the drive shaft or the driven shaft and of the piston have a specific relationship with respect to each other. The piston movement relative to the shaft is effected by a guide gearing. In this connection, several possibilities are known in the art. Generally, a toothed-wheel gearing is used, wherein an external gear having a smaller diameter rolls off in an internally toothed wheel having a larger diameter. In this case, one of the gear wheels is rigidly connected with the housing, and the other gear wheel is mounted at the piston. By means of the toothed-wheel gearing, the dimensions of the drive shaft are established, however, and it is not possible to use a continuous shaft for several pistons.

In order to obviate this disadvantage, specific guide gearings with gear wheels have been employed which were subdivided into a part within and apart without the side walls of the engine. Necessary therefor are spe cific complicated geared hind axles, planetary gearings, and hollow shafts. These supplementary elements represent a costly structural expenditure and considerably increase the inaccuracy clue to the inevitable play between the structural elements.

A further type of follower drive for the piston movement makes use of parts moved in guide rods. In this case, a reciprocating movement produced in the guide rods is transformed into a rotary movement. A follower drive system of this kind is based, for example, upon the principle of ellipse formation. It is a follower drive system of this kind to which the present invention is directed.

In the follower drive systems known heretofore, the center of the returning elements was positioned on a crank pin, in a manner similar to a connecting rod bearing in crankshafts of reciprocating engines. Such an arrangement, however, is unfavorable from the point of view of manufacturing techniques and also involves difficulties with regard to the mechanical stability of the shaft. For the operation thereof, the requirement exists that the stability or rigidity of the drive shaft be adapted to be selected as desired. For the manufacture, on the other hand, simplicity and economy are the prime considerations. Offsets or throws of the drive shaft are to be eliminated so as to obtain a continuous shaft on which even several pistons may be arranged in the mechanical assembly technique. Likewise to be eliminated are the difficulties of the offset shaft existing with respect to lubrication. A further requirement is that the highest possible degree of precision is intended to be assured with regard to the returning angle of the piston relative to the returning angle of the shaft. The same holds true for the precise position of the piston with respect to the housing so as to satisfy the conditions of the piston kinematics.

It is the object of the present invention to provide a follower drive and coordinated drive shaft in such a manner that the disadvantages referred to above are eliminated and so that the shaft, with a simple manufacture thereof, may be designed entirely according to the requirements with respect to stability.

This object is obtained, in accordance with the present invention, in that non-rotatably mounted on the drive shaft of the engine and eccentrically offset with respect thereto by the extent of the trochoid eccentricity is a cylindrical rotary body and a sleeve rotatably positioned thereon serves as a carrier for the parts of the follower drive system non-rotatably connected therewith and for the piston. Advantageously, the drive shaft and the cylindrical rotary body are integral. It is also possible, however, to use as a drive shaft, for example, a continuous tube or the like, and to eccentrically mount the rotary body thereupon and secure it onto the tube. The advantage of this arrangement with drive shaft and rotary body seated thereon is that the drive shaft is no longer delimited in its dimensions by the divided circles of gear wheels. The dimensions of the drive shaft and its supports within the housing may be selected entirely in accordance with the requirements of the stability thereof. A further significant advantage of this construction is that lubricant also may be supplied through a central bore in the drive shaft and distributed radially due to centrifugal force. Not only the lubrication but also cooling can be effected in the same manner. Lubricating oil and cooling oil are very easy to guide on the cylindrical rotary body up to the sleeve bearing. Through annular grooves on the inside of the sleeve and through perforations of the sleeveextending from these grooves, the lubricant travels to the parts of the follower drive connected to the sleeve and to the bearings thereof in the structural elements of the guide rods.

One embodiment of the present invention will now be further described hereinbelow with reference to the accompanying drawings. Used therein as the basis of the rotary piston engine selected as an example is the simplest trochoid, namely an epitrochoid l 1, i.e. a cardioid, for the piston shape.

FIG. 1 is a schematic longitudinal cross-sectional view through a rotary piston engine;

FIG. 2 is a cross-sectional view taken along line II/II in FIG. 1 with the parts of the follower drive;

FIG. 3 is a cross-sectional view taken along line III/III in FIG. 1 with the working chamber and the rotary piston, and

FIG. 4 illustrates a further development of FIG. 1 with two rotary pistons.

Shown in FIG. 1 is the continuous drive shaft 1 with the central axis M thereof. Eccentrically mounted thereon is a cylindrical rotary body 2. The central axis of the rotary body 2 is designated by M The two central axes of the drive shaft 1 and of the rotary body 2, i.e. the axes M and M extend parallel and are offset with respect to each other by the indicated extent of the trochoid eccentricity E. M simultaneously also represents the piston center. The drive shaft 1 is mounted in the housing 10, in a manner not further shown, at the two bearings 10'. A sleeve 3 is rotatably mounted on the rotary body 2. Rigidly mounted thereon are the parts 4 and 5 of the follower drive as well as of the rotary piston 6. These parts, i.e. the follower drive and the rotary piston, may be non-rotatably connected with the sleeve 3, for example by means of the keys 8. Further indicated in the housing 10 are also the radial sealing strips 7 which sealingly rest against the end face of the rotary piston 6. Outside of the housing 10, flywheel discs 9 are non-rotatably mounted on the drive shaft. With the aid thereof, a perfect balancing of the entire structure is readily possible. This balancing, however, is no part of the present invention and therefore has not been illustrated in any detail.

The drive shaft 1 contains a central bore 11 through which lubricating oil and/or cooling oil may be supplied. From this central bore 11 there extend radial bores 12 to the bearings in the housing 10. Provided in an analogous manner are bores in the rotary body 2 so that lubricating oil can flow to the bearing surface between the rotary body 2 and the sleeve 3. Through annular grooves 13 on the inside of the sleeve 3, the lubricating oil may be distributed over the entire circumference. Extending from the annular grooves 13, there lead further perforations 12' through the sleeve 3, and, adjacent thereto, also radial bores 12" through the eccentric discs 4 and 5 of the follower drive up to the bearing supports thereof into the frames 4' and 5 of thefollower drive. Also at the bearings of the eccentric discs 4 and 5 in the coordinated frames 4' and 5 thereof, annular grooves may be provided which have been identified herein with reference numeral 13'. As has been shown on the basis of the example of the eccentric disc 5, the frames 5 also may have bores in such a manner that lubricating oil may flow up to the guide rods 15. In this manner, lubricating oil is conveyed from a central supply via the bore 11 by means of centrifugal force up to the guide rods of the follower drive. Instead of annular grooves, spiral grooves may be provided in the guide rods of the frames 4' and 5 which render possible a uniform distribution of the lubricating oil along the guide rods 14 and 15. In the entire path, the lubricating oil is conveyed by centrifugal force only and does not have to counteract the centrifugal force at any point.

The operation of the follower gearing will be further explained hereinafter with reference to FIGS. 1 and 2.

Non-rotatably mounted on the sleeve 3 is an eccentric disc 4 having a circular shape. The eccentric disc 4 is rotatably mounted within a coordinated frame 4. Analogously, an eccentric disc 5 is mounted within a coordinated frame 5. The frame 4 is displaceably mounted in a pair of rods 14. The direction of the displacement has been indicated in FIG. 2 by a double arrow in the frame 4. The direction of displacement is parallel to the axial direction Y y. At a right angle to the vertically reciprocating movement just mentioned, i.e. parallel to the axial direction X shown, the frame 5 is displaceable in a reciprocating manner within a pair of guide rods 15. This direction of displacement again has been indicated by a double arrow. The axial directions X and Y,,,; designate the axial directions of the envelope curve to the trochoid. Instead of the pair of guide rods 14 and there suffices, under certain circumstances, in each case also one guide rod 14 and 15 alone for an exact guide of the reciprocating parts.

Other constructions of the guide rods within the housing are equally possible without departing from the spirit and scope of the presentinvention. The centers of the eccentric discs 4 and 5 are displaced, as compared to the central axis-M of the rotary body 2, in opposite directions by the extent of the trochoid eccentricity E. The centers of the eccentric discs 4 and 5 have not been specifically shown in the drawing for the sake of greater clarity of illustration. Due to the straight reciprocating movement of the frames 4' and 5 in the Y direction and in the X direction, there results a rotary movement of the rotary body 2, and therewith also of the drive shaft 1. The rotation takes place about the axis M in the direction of the arrow D, as shown. At that time, the sleeve 3, rotatably mounted on the rotary body 2, rotates with the eccentric discs 4 and 5 in the opposite direction. This direction of rotation has been indicated with the arrow D FIG. 3 schematically shows the working chambers Va, and Va of a rotary piston engine with the piston 6 mounted therein. The other delimitation of the working chambers is illustrated by the envelope curve 16. Also shown in FIG. 3 are again the axial directions X and YHQ. Mounted in the Y, axis are the radial sealing strips 7 of the rotary piston engine. The outline of the drive shaft 1 has been indicated in phantom within the rotary body 2. The central lubricating bore 11 together with the radial bores 12 is also illustrated. The piston 6 is non-rotatably connected with the sleeve 3. The connection is by means of a key 8. Because of the rigid connection between the piston and the sleeve, the piston 6 also rotates in the same direction D as the eccentric discs 4 and 5. For the trochoidal engine selected here as an example with sliding engagement and the simplest trochoid form or shape, namely a cardioid, the rotary movements D of the drive shaft 1 and D of the piston 6 as shown precisely represent the positive relative movement being important for this type of engine.

The coordinated follow-up movements also may be achieved in an analogous fashion for other trochoid forms or shapes.

The embodiment of FIG. 4 corresponds essentially to that of FIG. 1, but in this case a longer sleeve 3 is mounted on the continuous drive shaft 1, and an additional piston 6' is mounted thereon. The piston 6' assumes precisely the same angular position as the piston 6. It is thus possible by means of a continuous drive shaft 1 and a single common follower drive to control several rotary pistons with the eccentric discs 4 and 5, with the frames 4 and 5 thereof, as well as their guide rods 14 and 15. It is readily apparent from FIG. 4 that, with the aid of the construction described herein of a continuous drive shaft and an eccentrically mounted rotary body thereon, several pistons may be mounted in a simple manner according to the mechanical assembly principle or technique and controlled. A further modification of FIG. 4 is that the guide rods 14 and 15 are equipped with central bores 14 and 15'. Through these central longitudinal bores, lubricating oil may be supplied. This lubricating oil flows through radial bores 15" and makes possible a simple lubrication of the guide rods. It is important in this connection that the bores 15 are only in the section of the guide rods 14 and 15 constantly surrounded by the reciprocated frames 4' and 5' of the follower drive.

By virtue of the arrangement described hereinabove, the requirement relative to a sufficient stability of the drive shaft is perfectly satisfied. The shaft may be se- 7 lected practically entirely in accordance with the spe-- cific requirements of the respectively involved rotary piston engine. The manufacture of the drive shaft and of the associated rotary body is extremely simple, and the highest degree of precision with respect to the returning angle between the piston and the drive shaft as well as between the piston and the housing is attainable. The inaccuracies due to the harmful play between the teeth of the various parts of a toothed-wheel gearing are completely eliminated. The total structural expenditure is considerably reduced. Furthermore, the

assembly of the drive shaft and the piston in the engine is considerably facilitated because of the mechanical assembly principle being possible.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. In a rotary piston engine of trochoidal construction having an inlet, an outlet, a drive shaft, and a piston designed as an epitrochoid l 1, an inner housing wall conforming to the outer envelope curve of the epitrochoid, and a follow-up drive effecting the piston movement, said follow-up drive including at least two straight guides having axial directions which cross the longitudinal engine axis, a reciprocatable element associated with each axial direction and containing a rotatable disc, said disc being mounted eccentrically to the engine axis and being non-rotatable with respect to each other,

the improvement which comprises cylindrical body means non-rotatably mounted on the engine drive shaft and eccentrically offset with respect thereto by the extent of the trochoid eccentricity, said cylindrical body having a radius at least equal to the trochoid eccentricity plus the radius of the engine drive shaft, and

sleeve means rotatably mounted on said cylindrical body means and serving as a carrier for elements of the follow-up drive non-rotatably connected thereto, and for the piston.

2. A rotary piston engine according to claim 1 having bores in said follow-up drive that terminate in spiralshaped grooves.

3. A rotary piston engine according to claim 1 including a plurality of pistons mounted on said sleeve means in the same angular position. 

1. In a rotary piston engine of trochoidal construction having an inlet, an outlet, a drive shaft, and A piston designed as an epitrochoid 1 : 1, an inner housing wall conforming to the outer envelope curve of the epitrochoid, and a follow-up drive effecting the piston movement, said follow-up drive including at least two straight guides having axial directions which cross the longitudinal engine axis, a reciprocatable element associated with each axial direction and containing a rotatable disc, said disc being mounted eccentrically to the engine axis and being non-rotatable with respect to each other, the improvement which comprises cylindrical body means nonrotatably mounted on the engine drive shaft and eccentrically offset with respect thereto by the extent of the trochoid eccentricity, said cylindrical body having a radius at least equal to the trochoid eccentricity plus the radius of the engine drive shaft, and sleeve means rotatably mounted on said cylindrical body means and serving as a carrier for elements of the follow-up drive non-rotatably connected thereto, and for the piston.
 2. A rotary piston engine according to claim 1 having bores in said follow-up drive that terminate in spiral-shaped grooves.
 3. A rotary piston engine according to claim 1 including a plurality of pistons mounted on said sleeve means in the same angular position. 